try not to get hit. if you do then try to heal ASAP. You will need to use you fists, dark jak, and your gun to defeat him. If you run out of ammo then use your fists and dark jak if you have it. Once you get ammo then continue shooting at him. I took me a while to be able to defeat him but i was able to do it after a few times. I always say "If at first you don't succeed try, try again."